CVE-2026-53671
CVE-2026-53671 is a critical-severity vulnerability with a CVSS 4.0 base score of 9.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-682.
Key facts
- Severity: Critical (CVSS 4.0 base score 9.3)
- EPSS exploit prediction: 1% (41st percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-682
- Published:
- Last modified:
Description
PREVAIL is a Polynomial-Runtime EBPF Verifier using an Abstract Interpretation Layer. Prior to version 0.2.4, the abstract transformer in prevail treats writes through a T_CTX-typed base register as a silent no-op: do_mem_store in src/crab/ebpf_transformer.cpp only models T_STACK stores, and the checker's T_CTX bounds arm never tests AccessType::write. An attacker can craft an eBPF program that overwrites a context field (e.g., ctx->data), reload that field typed as T_PACKET, and dereference an attacker-controlled address — and prevail will report the program as safe. This issue has been patched in version 0.2.4.
Frequently asked questions
- What is CVE-2026-53671?
- PREVAIL is a Polynomial-Runtime EBPF Verifier using an Abstract Interpretation Layer. Prior to version 0.2.4, the abstract transformer in prevail treats writes through a T_CTX-typed base register as a silent no-op: do_mem_store in src/crab/ebpf_transformer.cpp only models T_STACK stores, and the checker's T_CTX bounds arm never tests AccessType::write. An attacker can craft an eBPF program that overwrites a context field (e.g., ctx->data), reload that field typed as T_PACKET, and dereference an attacker-controlled address — and prevail will report the program as safe. This issue has been patched in version 0.2.4.
- How severe is CVE-2026-53671?
- CVE-2026-53671 has a CVSS 4.0 base score of 9.3, rated critical severity.
- Is CVE-2026-53671 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-53671?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2026-53671 published?
- CVE-2026-53671 was published on 2026-09-02 and last updated on 2026-09-09.
References
- https://github.com/vbpf/prevail/commit/de65234f67d2608b54d12571edb585ead224363c
- https://github.com/vbpf/prevail/releases/tag/v0.2.4
- https://github.com/vbpf/prevail/security/advisories/GHSA-65rv-h458-cq99
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